Ibn Ishaq - Sirat Rasul Allah - (Translator: A. Guillaume)
The most earliest biography of Prophet Muhammad, written by Ibn Ishaq about 200 years after Muhammad's death. WARNING: There are some things written in this book which have no source while other things written are based on weak sources (i.e. weak Hadiths). The book gives the sources, and other times doesn't provides sources. Other scholars (i.e. Ibn Hisham) who came after Ibn Ishaq analysed some of the material written in this book based on historical sources we have, and claimed the weak sources in his book to have no authentic claimed proof.
SCHOLARS WHICH CONDEMN IBN ISHAQ:
Unfortunately, Ibn Ishaq excited the enmity of Malik b. Anas, for whose work he showed his contempt, and it was not long before his own writings and his orthodoxy were called in question." (Alfred, Guillaume. The Life of Muhammad - A Translation of Ibn Ishaq's Sirat Rasul Allah - Oxford University Press, 2004 - Introduction, Page XIII).
"Adh-Dhahabi also listed some of the major scholars of Islam who refuted Ibn Is'haq's reliability in Hadith narrations. Imam Malim, for instance, called Ibn Is'haq a liar and Yahya Ibn Saeed al-Ansari, as well as al-Amash refuted one of Ibn Is'haq's narrations by saying that he lied." Imam Ahmad also said that Ibn Ishaq did not care from whom he collected Hadiths. Imam Ibn Numair said that Ibn Ishaq reported false Hadiths from unknown narrators." (Shaykh Jalal Abu Al Rub - The Prophet of Mercy - Chapter 2 - Page 10).
"Allah has provided evidence (i.e. Isnad) establishing the authenticity or lack thereof of the narrations that are necessary in matters of the religion. It is well known that most of what was reported in aspects of Tafsir (commentaries on the Qur'an) is similar to narrations reporting Maghazi (or Seerah) and battles, promoting Imam Ahmad to state that three matters do not have Isnad: Tafsir, Mala'him (i.e. great battles), and Maghazi. This is because most of their narrations are of the Maraseel (plural for Mursal) type, such as narrations reported by Urwah Ibn az-Zubair, ash-Sha'bi, az-Zuhri, Musa Ibn Uqbah and Ibn Ishaq. (Shaykh Ibn Taymiyyah - Majmu' Al Fataawa - Volume 13 - Page 345).
"Imam Malik was not the only contemporary of Ibn Ishaq's to have problems with him. Despite writing the earliest biography of Prophet Muhammad, Scholars such as al-Nisa'I and Yahya b. Kattan did not view Ibn Ishaq as a reliable or authoritative source of Hadith." (Jones, J.M.B. Ibn Ishak. Vol. IV, in Encyclopaedia of Islam, edited by Ch. Pellat, and J. SchachtV.L.M.B. Lewis. London: Luzac & Co., 1971: pages 810-811).
"Imam Ahmad Ibn Hanbal discounted the reliability of Ibn Ishaq if he alone narrates a Hadeeth. Also, Imams Yahya Ibn Ma`een (in another narration from him), an-Nasaii and ad-Daraqutni stated that Ibn Ishaq was weak in Hadeeth. The great Imam of Sunnah, Imam A`hmad Ibn Hanbal, also added that Ibn Is`haq's narrations are not accepted if they are about the Sunan."
Problems with Ibn Ishaq: http://www.answering-christian-claims.com/The-Problems-With-Ibn-Ishaq.html
Unreliability of Ibn Ishaq: http://answering-christian-claims.com/Jalal-Abu-Al-Rub-and-the-Unreliablity-of-Ibn-Ishaq.html
Fale/Unreliable Stories In Ibn Ishaq: http://answering-christian-claims.com/False_Stories_About_Prophet_Muhammad.html
"Just because something is early, doesn't mean it's authentic. If something is early, it just means its early. It has to be early AND authentic. It's possible that something is early and false/unauthentic." - Bassam Zawadi, one of the best Muslim apologists.
More biographies of Prophet Muhammad: http://www.archive.org/details/SeerahIbnHisham http://www.scribd.com/doc/3105678/The-Millennium-Biography-of-Prophet-Muhammad http://d1.islamhouse.com/data/en/ih_books/single/en_The_Sealed_Nectar.pdf